Abstract

CUEVA-RODRIGUEZ, Alejandro et al. Design and use of a portable system for measuring soil respiration in ecosystems. Terra Latinoam [online]. 2012, vol.30, n.4, pp.327-336. ISSN 2395-8030.

Soil respiration (RS) is the second largest CO2 exchange pathway between the soil surface and the atmosphere, just after photosynthesis. CO2 diffusion from the soil into the atmosphere is a function of other factors such as humidity and soil texture, causing RS to vary spatially within ecosystems and making its study difficult. To advance knowledge about the spatial patterns of RS, it is necessary to develop agile portable systems. The objective of this work was to design a portable system for determining soil respiration from different ecosystems. The system was based on the closed dynamic chambers technique, which creates a closed ambient between the soil surface and an infrared gas analyzer to monitor the increase in CO2 concentration during 150 seconds. In order to test the system, soil samples were collected below canopies of representative species of a xeric shrubland (Acacia cochliacantha, an association of Fouquieria-Jatropha, and Parkinsonia praecox) as well as in exposed areas, in a wetting/drying cycle. The results show that under humid conditions (10% Vol.) soils influenced by P. praecox have the largest RS fluxes (8.8 ± 1.42 μmol m-2 s-1), the sites influenced by Fouquieria-Jatropha showed the smallest RS fluxes (3.9 ± 1.23 μmol m-2 s-1) and A. cochliacantha sites and the exposed areas showed similar intermediate values (5.7 ± 1.23 μmol m-2 s-1 y 5.6 ± 1.23 μmol m-2 s-1 respectively). During dry days, RS was below 0.5 μmol m-2 s-1 even though RS was higher under A. cochliacantha. The variation observed is within the ranges reported in the literature, demonstrating that the system has the sensitivity needed to detect spatial and temporal variations in RS.

Keywords : CO₂; carbon; ecosystem fluxes; respiration chambers; Sonora.

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